In a normally distributed group, an examinee scores one SD above the mean. What shall be her/his percentile score?

Correct option is C

The correct answer is 84.
1. In a normal distribution, the mean, median, and mode all lie at the center of the distribution. A score that is one standard deviation (SD) above the mean typically corresponds to the 84th percentile.
2. This is because, in a normal distribution, about 68% of the scores fall within one standard deviation of the mean (34% on each side of the mean). When you move one standard deviation above the mean, you capture about 84% of the data, leaving 16% above it.

Information Booster
1. Qualities of the Normal Probability Curve:
1.1. Symmetry: The normal distribution is perfectly symmetrical around the mean. This means the left side of the curve is a mirror image of the right side.
1.2. Bell-shaped curve: The normal distribution is often depicted as a bell-shaped curve, where most of the values cluster around the mean.
1.3. Mean, Median, Mode are the same: In a normal distribution, the mean, median, and mode are all located at the same point in the center of the distribution.
1.4. 68-95-99.7 Rule: This rule states that approximately 68% of the data falls within one standard deviation of the mean, 95% falls within two standard deviations, and 99.7% falls within three standard deviations.
1.5. Tails extend infinitely: The tails of a normal distribution curve never touch the horizontal axis, meaning that theoretically, the distribution extends infinitely in both directions.
1.6. Standard deviation measures spread: The spread of data points in a normal distribution is measured by the standard deviation. A higher standard deviation means the data is more spread out, while a lower standard deviation means the data is more concentrated around the mean.
2. Measures of Central Tendency:
2.1. Mean: The mean is the arithmetic average of a set of numbers and is the most commonly used measure of central tendency. In a normal distribution, the mean is the point at which the curve peaks.
2.2. Median: The median is the middle value of a dataset when the values are arranged in ascending or descending order. In a normal distribution, the median coincides with the mean.
2.3. Mode: The mode is the value that occurs most frequently in a dataset. For a perfectly normal distribution, the mode is the same as the mean and median.
2.4. Relationship to Normal Distribution: In a normal distribution, all three measures of central tendency (mean, median, mode) are located at the same point in the center of the distribution, reflecting the symmetry of the curve.